[torchcodec] delay device map init to runtime and fix targets

Summary:
We were running into the Static Initialization Order Fiasco: https://en.cppreference.com/w/cpp/language/siof

We avoid this problem by delaying the initialization of the device map until runtime.

Differential Revision: D72722867

Author: scotts

src/torchcodec/_core/DeviceInterface.cpp

@@ -11,8 +11,9 @@
 namespace facebook::torchcodec {
 
 namespace {
+using DeviceInterfaceMap = std::map<torch::DeviceType, CreateDeviceInterfaceFn>;
 std::mutex g_interface_mutex;
-std::map<torch::DeviceType, CreateDeviceInterfaceFn> g_interface_map;
+std::unique_ptr<DeviceInterfaceMap> g_interface_map;
 
 std::string getDeviceType(const std::string& device) {
   size_t pos = device.find(':');
@@ -28,11 +29,18 @@ bool registerDeviceInterface(
     torch::DeviceType deviceType,
     CreateDeviceInterfaceFn createInterface) {
   std::scoped_lock lock(g_interface_mutex);
+  if (!g_interface_map) {
+    // We delay this initialization until runtime to avoid the Static
+    // Initialization Order Fiasco:
+    //
+    //   https://en.cppreference.com/w/cpp/language/siof
+    g_interface_map = std::make_unique<DeviceInterfaceMap>();
+  }
   TORCH_CHECK(
-      g_interface_map.find(deviceType) == g_interface_map.end(),
+      g_interface_map->find(deviceType) == g_interface_map->end(),
       "Device interface already registered for ",
       deviceType);
-  g_interface_map.insert({deviceType, createInterface});
+  g_interface_map->insert({deviceType, createInterface});
   return true;
 }
 
@@ -45,14 +53,14 @@ torch::Device createTorchDevice(const std::string device) {
   std::scoped_lock lock(g_interface_mutex);
   std::string deviceType = getDeviceType(device);
   auto deviceInterface = std::find_if(
-      g_interface_map.begin(),
-      g_interface_map.end(),
+      g_interface_map->begin(),
+      g_interface_map->end(),
       [&](const std::pair<torch::DeviceType, CreateDeviceInterfaceFn>& arg) {
         return device.rfind(
                    torch::DeviceTypeName(arg.first, /*lcase*/ true), 0) == 0;
       });
   TORCH_CHECK(
-      deviceInterface != g_interface_map.end(), "Unsupported device: ", device);
+      deviceInterface != g_interface_map->end(), "Unsupported device: ", device);
 
   return torch::Device(device);
 }
@@ -67,11 +75,11 @@ std::unique_ptr<DeviceInterface> createDeviceInterface(
 
   std::scoped_lock lock(g_interface_mutex);
   TORCH_CHECK(
-      g_interface_map.find(deviceType) != g_interface_map.end(),
+      g_interface_map->find(deviceType) != g_interface_map->end(),
       "Unsupported device: ",
       device);
 
-  return std::unique_ptr<DeviceInterface>(g_interface_map[deviceType](device));
+  return std::unique_ptr<DeviceInterface>((*g_interface_map)[deviceType](device));
 }
 
 } // namespace facebook::torchcodec